This invention relates generally to a muffler for exhaust gas and more particularly, but not by way of limitation, to a muffler used with an aviation engine to reduce exhaust gas noise.
Heretofore, there have been various structural designs of exhaust mufflers for automotive and aircraft engines. These mufflers are primarily designed to reduce back pressure to the cylinders of the engine. By reducing back pressure, the horsepower of the engine is increased and the engine life is improved.
With the recent advent of federal laws requiring the reduction of sound and air pollution from combustion engines, it has been found that the older muffler designs in some instances are not sufficient to meet the new government standards.
A typical prior art muffler used with aviation engines is disclosed in U.S. Pat. No. 3,043,098 to Hannon, wherein an exhaust heater-muffler combination is used in combination with a four cylinder or six cylinder aircraft engine. This type of muffler is designed to reduce back pressure to the engine. The Hannon muffler divides an inner core can into separate chambers by a splitter plate. The exhaust gasses are received through exhaust tubes at both ends of the separate chambers. By preventing the exhaust gas received in the separate chambers from opposing each other, the back pressure to the cylinders of the engine is reduced. This type muffler does not provide a sound attenuator for increasing the back pressure within acceptable limits so that the sound frequency of the exhaust gas may be increased and the acoustic energy is more easily attenuated when exhausted to the atmosphere.